Donald J. Trump rarely, if ever, acknowledges he might be losing at anything. He expressed bewilderment at a poll during the primary race that showed him behind in the Iowa caucuses. He often invokes unscientific polls as examples of his strength, and mentions surveys that have questionable methodology.

So it was surprising when Mr. Trump, the presumptive Republican presidential nominee, said on Thursday night that he is not beating Hillary Clinton in the most recent presidential polls.

“I’m four down in one poll, three and a half in another that just came out, and I haven’t started yet,” Mr. Trump, the presumptive Republican presidential nominee, said in a phone interview on Thursday night, a thought he volunteered as he dismissed concerns from Senate Republicans that he may be a drag on their candidacies in the fall.

“And I have tremendous Republican support,” Mr. Trump said. “Unfortunately they never talk about that, they talk about the few rebels.”

Mr. Trump did not specify which polls he was referring to, although he mentioned the Real Clear Politics average at another point. But Mr. Trump has not led a national poll throughout the month of June, with Mrs. Clinton’s lead ranging from 3 to 12 percentage points, depending on the survey. On Friday afternoon, Mr. Trump posted on Twitter a poll and added, “Thank you!” But even that survey showed him a couple of percentage points behind Mrs. Clinton.

Despite his historically high negative ratings, Mr. Trump suggested he has plenty of time to turn things around.

“I think I’m going to help,” Mr. Trump said of the Senate candidates. And he suggested that senators who were lagging in polls themselves had troubles long before he became the nominee.